Impact and mitigation of emergent diseases on major UK insect pollinators

点击翻译按钮获取中文摘要

The mysterious death of thousands of honey bee colonies in the USA in the winter of 2005/06, termed Colony Collapse Disorder, focused media attention on the plight of bees, the world's primary pollinators. In the UK, both the honey bee and the 24 species of bumble bee play a major role in crop and wildflower pollination, and both have been suffering serious declines. Exotic (non-native) and newly emergent (native, but with increasing virulence) diseases are considered a major cause of decline in bees and consequently they are one of the greatest challenges to bees in the UK. The single-celled microsporidian 'fungus' Nosema ceranae is an exotic infectious disease of the honey bee that primarily attacks the gut of the bee. We have shown that it has spread worldwide, including the UK, within the last ca. 10 years, and it has been implicated in honey bee colony collapses in the USA (2005/06) and Spain (2007/08). Deformed Wing Virus (DWV) is the major disease organism associated with Varroa destructor mites of honey bees. This emergent disease replicates inside the bee, causing deformed wings and reduced longevity and is responsible for considerable honey bee colony mortality in the UK. Both disease organisms have recently been detected in bumble bees. Thus, both N. ceranae and DWV pose major threats to the UK's principal pollinators. Investigations of pollinator diseases typically focus on single-species interactions (one disease organism and one pollinator species). However, most parasites have multiple hosts and most hosts have multiple parasites. Here, we will take a multidisciplinary, ecological systems-based approach to understand the virulence (e.g. reduced longevity) and transmission of these two major disease organisms, N. ceranae and DWV, and detrimental synergies between them, on the UK's major pollination service providers: the honey bee and bumble bees. We will undertake laboratory epidemiological experiments (in which we look at the impact of a disease organism(s) on its host and the progression of disease from initial infection through to host mortality or recovery), state-of-the-art 'post-genomic' analyses and high-resolution radar tracking of individual insects to determine disease virulence and transmission. Using these data, we will parameterise a novel epidemiological model that will allow risk assessment of these emergent diseases on UK pollinators. Taking advantage of the complete genomes of both N. ceranae and DWV, we will undertake country-wide screening of pollinators to provide the evidence base of current disease strain prevalence. We will also refine innovative approaches for combating disease impacts. Specifically we will investigate the role of 'lactic acid bacteria' (the 'good guys' found naturally in healthy bee guts) and so-called RNAi technology (=RNA interference - short stretches of RNA that may interfere with viral replication inside a host) in curing bees of N. ceranae and DWV, which would provide long-term sustainable solutions to these disease organisms. For ca. £1.6 million (75% FEC), this interdisciplinary project will combine expertise from three leading UK bee and pollination research groups at Queen's University Belfast, Royal Holloway University of London and Rothamsted Research with mathematical modellers (Royal Holloway), pioneering microbiologists at the University of Lund (Sweden) and the world leader in RNAi technologies for bee diseases: Beeologics (USA). It will elucidate the impact and epidemiology of two increasingly important parasites on the UK's principal insect pollinators. Results will provide the evidence base for policy on disease mitigation strategies for government (conservation and agricultural advisory bodies) and major stakeholders (beekeepers, bumble bee importers). As well as serving as a model study of emergent pollinator diseases, project results will feed directly into husbandry practices and approaches to mitigate disease impact.